Conventional low density polyethylene (LDPE) has good processability, but when used in film and/or extrusion coating applications, increased melt strength and higher G′ performance is still desired. U.S. Pub. No. 2008/0242809 discloses a process for preparing an ethylene copolymer in a tubular reactor at a peak temperature of 290° C.-350° C. The comonomer is a di- or higher functional (meth)acrylate WO 2007/110127 discloses an extrusion coating composition comprising an ethylene copolymer polymerized in a tubular reactor at a peak temperature of 300-350° C. The comonomer is a bifunctional α, ω-alkadiene. WO97/45465 discloses an unsaturated ethylene copolymer, method for producing it, and its use for producing crosslinked structures. The unsaturated ethylene copolymer comprises a polymer, obtained by radical polymerization through a high-pressure process, of ethylene, and at least one monomer that is copolymerizable with ethylene and includes a diunsaturated comonomer of the formula (I) H2C═CH—O—R—CH═CH2, where R=—(CH2)m-O—, —(CH2CH2O)n-, or —CH2-C6H10-CH2-O—, m=2-10, and n=1-5. Preferably, this comonomer is 1,4-butanediol divinyl ether. WO2014/003837 discloses an ethylene-based polymer made by reacting ethylene and at least one asymmetrical polyene having an “alpha, beta unsaturated end” and a “C═C double bond end” in the presence of a free-radical initiator. The impact of the above-described multifunctional components on the final polymer through coupling and/or branching reactions is complex, and depends on the type and reactivity of the functional groups. A vinyl functional group will act as a comonomer and incorporate into a polymer chain/molecule. Chain Transfer Agent (CTA) functionality will either start the formation of a new polymer molecule, or initiate, after incorporation of the monomeric group, the formation of a Long Chain Branch (LCB) or T-branch. For a multi- and/or bifunctional component to impact polymer rheology, it is important that (1) at least two functional groups of the component molecule react and (2) effective branches are formed in the polymer.
WO2013/059042 describes the use of ethylene and/or CTA feed distribution to broaden molecular weight distribution (MWD) and increase melt strength, while keeping all other process conditions constant The use of highly reactive multifunctional components is also subject to other process and/or polymer concerns, such as stability of the component, premature polymerization and fouling formation potential in the compression and preheating sections, reactor fouling, gel formation in polymer, process stability potentially leading to ethylene decomposition, and the like. Additional polymerizations are described in WO 2013/149699 and WO2013/149698. There remains a need for such processes in which low concentrations of coupling and/or branching components can be used to achieve the desired high G′ value products for film and extrusion coating applications, while avoiding or reducing undesired product and process issues, as product gels and process instability and/or fouling. Furthermore, the lower concentration of coupling and/or branching components leads to lower consumption and costs. These needs and others have been met by the following invention.